The present invention relates to an improved plastic bag construction and flexible fastener construction which incorporates pressure closable reopenable rib and groove elements. More particularly, the invention relates to an improved rib and groove fastener structure and method of opening the fastener structure which eliminates the need for pulling apart opposing flaps as has heretofore been necessary.
Reclosable zipper lock plastic bags generally are formed of flexible thin plastic film with front and side walls with the walls attached to each other along their sides and seams, and the walls attached along a bottom edge. The bag may be filled through the open bottom edge which is then sealed or may be filled through the top. Adjacent the top edge and extending fully across opposed confronting inner surfaces of the mouth of the bag are a pair of cooperatively interlocking fastener strip profiles formed with respective engageable rib and groove elements made of extruded plastic material. Examples of such bags and means of manufacture thereof are disclosed in U.S. Pat. Nos. 3,198,228, 3,291,177, 3,338,284 and 3,340,116. Plastic bags may have the zipper lock rib and groove elements integral with the bags or these zipper lock elements may comprise separate fastener strips which are attached to the top of bags. In either instance, the zipper lock rib and groove elements normally are extruded and are interlocked during manufacture for convenience of storage and handling. The rib and groove elements then must be separated for filling or for use. Typically, there are flange members extending above the rib and groove elements which flange members are gripped and pulled apart to separate the rib and groove for access to the interior of the bag.
Disadvantages are encountered in this manner of separating the rib and groove elements for opening the bag in that it is difficult to find and grasp the separate flange elements particularly when the bag is formed of a very thin plastic film. Also, if it is intended that the bags are to be handled by a machine and opened by machine for mechanical handling and filling, it is difficult to provide machine elements which will find and grip the flanges and pull apart the rib and groove elements.
Accordingly, it is an object of the present invention to provide an improved method and structure whereby interlocked rib and groove bag closure elements may be separated rapidly and easily without the necessity of grasping the flanges to pull the rib and groove elements apart.
It is another object of the invention to provide a structure and means for separating rib and groove elements rapidly by the application of simple mechanical force such as gripping the elements between the thumb and forefinger and sliding the elements longitudinally relative to each other.